Induction of cytokines via NF-κB and p38 MAP kinase signalling pathways associated with the immunomodulation by Lactobacillus plantarum NDC 75017 in vitro and in vivo

Lactobacillus has been used as a functional food ingredient to improve health. The expression of the pro-inflammatory cytokines interleukin-1β (IL-1β), IL-6 and tumour necrosis factor-α (TNF-α) stimulated by Lactobacillus plantarum NDC 75017 were investigated in the Caco-2 cells and intestinal tract of mice. In vitro, three cytokines (IL-1β, TNF-α, IL-6) could be momentarily induced; increased to the maximum level at 2, 4 and 8 h, respectively; and then decreased. Similar regulation could also be observed in vivo, and the expression of all cytokines peaked on day 5. Moreover, a transient activation of toll-like receptors (TLRs) and phosphorylation of NF-κB p65 and p38 MAPK were detected in Caco-2 cells by stimulation of NDC 75017. Inhibitors of NF-κB and p38 MAPK significantly suppressed cytokine expression (P < 0.01). Results suggested that L. plantarum NDC 75017 could perform a beneficial immunomodulation involving the pro-inflammatory cytokines NF-κB and p38 MAPK. This strain could be applied as a new potential immunoregulatory agent in functional foods.